An improved apparatus and method are provided to apply coating material to at least portions of the inner surfaces of cans.
The insides of cans have previously been at least partially coated to ensure that material forming the cans is not exposed to the contents of the cans. Various apparatus for use in applying coating material to the insides of cans is disclosed in U.S. Pat. Nos. 3,726,711; 4,378,386; and 4,886,013.
During the operation of a can coating apparatus, particles of coating material tend to build up on the nozzle of a spray gun. Japanese Pat. No. 1,438,108 suggests that a solvent spray may be directed against the nozzle of the spray gun to wash away the coating material which adheres to the nozzle.
During operation of the can coating apparatus, the flow of coating material from the spray gun may be shut off for a period of time. While the spray gun is shut off, the material spray gun prevents cooling of the coating material in the spray gun, by continuously circulating the coating material through the spray gun. It has been suggested that the coating material in a spray gun be heated by also conducting a secondary flow of heated coating material through the spray gun in the manner disclosed in Japanese Patent Application No. 61-16537.